1. Field of the Invention
The present invention relates to a photographing module that includes an electrically controlled actuator, and more particularly, to a photographing module whose electrically controlled actuator uses a voice coil motor (VCM) structure.
2. Description of the Related Art
There are many electronic devices that require the installation of an actuator, such as mobile phones with vibration function, magnetic heads having a linear actuator, autofocus photographing modules, etc. For these devices, voice coil motors (VCMs) are the most common type of actuators used within. Since VCMs are not expensive and are able to achieve a precise movement, they are suitable short-range microactuators for use with electronic devices.
Referring to FIG. 1, a front view of a prior art photographing module 7 is shown. The photographing module 7 includes: a lens unit 8, an electrically controlled actuator 9 connected to the lens unit 8, an elastic member 10 connected to the electrically controlled actuator 9, an insulating piece 11 positioned above the elastic member 10, a pair of power supply terminals 12 soldered to the elastic member 10, and a photo sensor 13 positioned under the electrically controlled actuator 9. The electrically controlled actuator 9 comprises a fixed element 91, a movable element 92 positioned on the fixed element 91, and an electrical unit 93 positioned around the outside of the movable element 92. FIG. 2 shows a top view of a prior art elastic member 10 as described above, which comprises a fixed portion 101, an elastic portion 102 linked to the fixed portion 101, and a movable portion 103 linked to the elastic portion 102. As shown in FIG. 1, the elastic member 10 and the insulating piece 11 are positioned sequentially between the fixed element 91 and the movable element 92 of the electrically controlled actuator 9. The insulating piece 11 prevents the elastic member 10 from electrically communicating with other metal components; moreover, the insulating piece 11 provides additional strength to press on the elastic member 10 so that it can be secured at a proper position.
The fixed portion 101 of the elastic member 10 is connected to the fixed element 91 of the actuator 9. The movable portion 103 of the elastic member 10 is connected to the movable element 92 of the actuator 9. While the pair of power supply terminals 12 and the elastic member 10 are soldered together, the elastic member 10 also electrically communicates with the electrical unit 93 of the actuator 9 to transmit electricity thereto. The photo sensor 13 is positioned on the image side of the photographing module 7 and connected to the fixed element 91 of the actuator 9. When an external power source (not shown) is coupled to the pair of power supply terminals 12, power will flow sequentially through the terminals 12 and the elastic member 10 to the electrical unit 93 of the actuator 9, thereby leading to an axial displacement of the movable element 92. This axial displacement of the movable element 92 enables the lens unit 8 to move linearly along the optical axis and also enables the movable portion 103 of the elastic member 10 to move, further leading to a linear displacement of the elastic portion 102.
FIG. 3 shows a top view of another prior art elastic member 14. A pair of power supply terminals 144 is formed integrally into the elastic member 14 to become one piece; hence, the step in which terminals 144 are soldered to the elastic member 14 can be eliminated. The elastic member 14 comprises a fixed portion 141, an elastic portion 142, a movable portion 143, and a pair of power supply terminals 144.
Both of the prior art elastic members 10 and 14 described above are flat springs with an even thickness. As miniaturization is a continuing trend in the production of electronic products, components like the elastic members 10 and 14 may be required to have smaller spring constants and their thicknesses will become smaller as a result. However, as the spring constant of an elastic member reduces, so does its stiffness; in consequence, the elastic member tends to rupture more easily. It is thus important to manage the balance between the spring constant and the stiffness of an elastic member, particularly in a design where the elastic member and power supply terminals are combined together. In this kind of design, generally, the elastic member is expected to have a relatively small spring constant; however, this may lead to a small stiffness for the power supply terminals. Since power supply terminals may have to be bent during assembly, they will be subject to rupture more easily with a small stiffness, thereby causing wastes that increase the production cost. Moreover, as the elastic member 14 and the power supply terminals 144 both become thinner, poor electrical contact between the terminals 144 and an external power source tend to happen more frequently.
As such, there exists a need in the art to develop an improved elastic member that has a reduced thickness and overcomes the drawback of rupturing easily and poor electrical contact occurring to the power supply terminals on the elastic member. Such an improved elastic member may effectively lower the production cost accordingly.